Don't get me wrong. I love new gadgets! But they have to earn their keep. My wall radar device is basically just a stud finder. Would be delighted to carry around an infrared camera but it has got to beat my God-given senses. I just took a course on home energy scoring to make sure I wasn't missing something.
The tools used were an infrared camera, smoke pencil and a serious fan to help determine leakage. The image above is of an attic hatch in the summer. This is why I recommend a foam box over the hatch at every inspection (or a tent over attic stairs). The camera in the training also showed warm spots along the ceilings near the eaves. (Where gaps in insulation would be easily visible from the attic.) Cold spots can also mean moisture but not always. I prefer rigorous inspection of drainage outside combined with visible wetting evidence inside. The smoke pencil showed air coming through the hatch and the recessed light cans: duh!
In the training they did the leakage test for one house and the technician determined there was 30% leakage. He said. "That leaves lots of room for improvement." In the next segment the supervisor, not aware of the specifics for the previous test, says that at over 70% tightness you have to consider ADDING VENTILATION. The testing costs about $400 and that is before any contractors come in to add the costly and perhaps detrimental sealing suggestions.
As a mold tester I see the trade offs between sealing everything up and getting proper ventilation every day. I would much prefer to have good air than save a little on energy costs.
Your best values on energy savings are recommended in every one of my reports: cover the hatch, have about 15 inches of loose insulation in the attic, insulate outgoing ducts from the air handler, and replace windows when the seals are broken. (Please never use spray foam insulation: it's ugly, smelly, and hides water and structural damage.)
Best ways to improve ventilation are installing humidstatic switches to bathroom fans (instead of using dehumidifiers) and running the HVAC fan "ON" instead of "AUTO" ,when stuffy, and to never completely close any registers: especially those in the basement.